Question

In: Mechanical Engineering

A house that is losing heat to the 100C outdoors at an average rate of 50,000...

A house that is losing heat to the 100C outdoors at an average rate of 50,000 kJ/h is maintained at 220C at all
times during a winter night for 10 h. The house is to be heated by 50 glass containers each containing 20 L
(1L=10-3 m3
) of water that is heated to 80oC during the day by a solar heater. A thermostat-controlled 15-kW
back-up electric resistance heater turns on whenever necessary to keep the house at 220C. Analyse and
determine the following:
i. If the average solar intensity is 650 W/m2

and the solar heater has an efficiency of 80%, calculate the

area of solar heater to heat 20L of water from 220C to 800C in 8 hours.
ii. How long did the electric heating system run at night?
iii. Keeping 2nd law of thermodynamics in mind, what is the maximum efficiency of the back-up heater?
iv. If the heat provided by the back-up heater is provided using Carnot heat pump, determine the
reduction in electricity consumption.

Solutions

Expert Solution

samet mamat answered 6 months ago
Next > < Previous

Related Solutions

A house that is losing heat to the 100C outdoors at an average rate of 50,000...
A house that is losing heat to the 100C outdoors at an average rate of 50,000 kJ/h is maintained at 220C at all times during a winter night for 10 h. The house is to be heated by 50 glass containers each containing 20 L (1L=10-3 m3 ) of water that is heated to 80oC during the day by a solar heater. A thermostat-controlled 15-kW back-up electric resistance heater turns on whenever necessary to keep the house at 220C. Analyse...
A Carnot heat pump moves heat to a warm house at 24°C at a rate of...
A Carnot heat pump moves heat to a warm house at 24°C at a rate of 300kW. The heat is pumped from the outside air at 7°C. What is the power required by the heat pump? What is the rate of change of entropy for each of the thermal reservoirs (the house, and the outside air)? Does this heat pump satisfy the second law of thermodynamics increase of entropy principle?
A heat pump is used to heat a house with an indoor temperature of 21 ◦C....
A heat pump is used to heat a house with an indoor temperature of 21 ◦C. Assume the outdoor temperature is -9 ◦C. What is the maximal energy that could be delivered to the house in one second if the work done on the heat pump is 1500 W (1500 J/s)? (a) 3000 J (b) 3500 J (c) 15.0 kJ (d) 200 J (e) 10.7 kJ
4) In 1970, an average house in Cupertino cost $41,000. a ) If the average house...
4) In 1970, an average house in Cupertino cost $41,000. a ) If the average house appreciates in value at 3.3% annually for the past 18 years, what is the price of that house in 1987? b) Suppose that your property tax was $250 and has increased by 3.5% annually, how much property tax would you have paid over the last 18 years for the house. 5) Suppose further that your maintenance expense during the first year was $200 and...
How is the unemployment rate defined? a.      The rate at which workers are losing their jobs...
How is the unemployment rate defined? a.      The rate at which workers are losing their jobs at a given time b.      The percentage of the population that is unemployed at a given time c.      The percentage of the labor force that is unemployed at a given time d.      The fraction of the working-age population who do not have a job, expressed as a percentage __________ 2.      Sources of growth in total factor productivity include all of the following except ____________....
1.a/ A house is heated at 22oC and has an average outdoor air infiltration rate of...
1.a/ A house is heated at 22oC and has an average outdoor air infiltration rate of 0.15 ACH at standard operating conditions. If the average temperature outside over three months (91 days) is 2oC what would be the approximate energy consumption due to natural air infiltration? The house is 250 m2 in area and has 8 foot high ceilings throughout. b/If the house is being heated by a 100% efficient electric baseboard heater, what would be the savings due to...
It costs $180 to heat a house with electricity in a typical winter month. (Electric heat...
It costs $180 to heat a house with electricity in a typical winter month. (Electric heat simply converts all the incoming electrical energy to heat.) Part A What would the monthly heating bill be following conversion to an electrically powered heat-pump system with COP=3.1? dollars = ?
You are planning to buy a house today. The house costs $350,000. You have $50,000 in...
You are planning to buy a house today. The house costs $350,000. You have $50,000 in cash that you can use as a down payment on the​ house, but you need to borrow the rest of the purchase price. The bank is offering a 30​-year mortgage that requires annual payments and has an EAR of 5% per year. What will be your annual mortgage​ payment?
Part A You are thinking of purchasing a house. The house costs $350,000. You have $50,000...
Part A You are thinking of purchasing a house. The house costs $350,000. You have $50,000 in cash that you can use as a down payment on the house, but you need to borrow rest of the purchase price. The bank is offering a 20-year mortgage that requires monthly payments and has an annual interest rate of 5% per year. Determine your monthly payments if you sign up for this mortgage. Draw the amortization schedule, monthly, using Excel. Calculate the...
Home is where the Heat is The walls of a house are made of a 10...
Home is where the Heat is The walls of a house are made of a 10 cm layer of brick, 10 cm of fiberglass insulation and 1cm of drywall. Thermal conductivity values: Brick: 1.31 W/m*K Fiberglass : 0.04 W/m*K dry wall : 0.17 W/m*K a) Calculate the thermal conductivity of a 1 m 2 section of wall. b) Find the relationship between the thermal conductivity, k, in W/m*K and the thermal resistance = R in (m^2 *K)/W. In order to...
ADVERTISEMENT
Subjects
ADVERTISEMENT
Latest Questions
ADVERTISEMENT